Shown here is a Diamond Medal barrel reservoir pen with small sac/bulb inside. The button rotates a mechanism to compress the sac. This pen has an odd ink shut off piece on the nib too!
The button and pressure bar removed to demonstrate its action
Shown here is a Diamond Medal barrel reservoir pen with small sac/bulb inside. The button rotates a mechanism to compress the sac. This pen has an odd ink shut off piece on the nib too!
